Aerial drop equipment



July 12, 1955 R. M. STANLEY AERIAL DROP EQUIPMENT 2 Sheets-Sheet l Filed Aug. 21. 1953 INVENTOR. 9055/27/14 STA/v4 EV BY H ,MQM,

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July 12, 1955 R M STANLEY 2,712,913

AERIAL DROP EQUIPMENT Filed Aug. 21, 1955 2 Sheets-Sheet 2 I o n 5 fi 4 g llllll IN VEN TOR. Hos/5R7 M frA/VL EV BY @W M,My@-W,

United rates 2,711,913 Patented July 12, 1955 ice AERIAL ERG? EQUIPMENT Robert 1%. Stanley, Bufiaio, N. Y., assignor to St niey Aviation Corporation, Butfaio, N. Y.

Application August 21, 1953, Serial No. 375,804 6 (Claims. (Cl. 244-138) their limited capacities for ground impact energy dissipation; and it is a primary object of the present invention to provide an improved landing shock-absorbing device for use under aerial drop platforms or the like.

Another object of the invention is to provide a device as aforesaid which embodies novel automatically-controlled mechanism for greatly increasing the impact energy-absorbing capacity of equipment employing air bag devices of minimum size.

Another object is to provide an improved ground contact anticipation control device for automatically pressurizing or supercharging the energy absorbing cells of the equipment at the time of landing.

Another object of the invention is to provide an improved device as aforesaid which is adapted to be relatively inexpensively fabricated, and which is rugged and sure in operation.

Other objects and advantages of the invention will appear in the specification hereinafter.

In the drawing:

Fig. 1 is an elevational view of an aerial drop unit embodying features of the present invention;

Fig. 2 is a fragmentary transverse vertical section, on an enlarged scale, through a portion of the landing shockabsorbing component of the aerial drop unit;

Fig. 3 is a fragmentary horizontal section taken along line lIIllI of Fig. 2;

Fig. 4 is a vertical sectional view through a portion of a ground contact anticipation control mechanism for the unit;

Fig. 5 is a horizontal section through the mechanism of Fig 4; and

Fig. 6 is a diagrammatic illustration of a suitable wiring circuit and control system in conjunction with the mechanism of Figs. 4 and 5 for controlling pressurization of the shock-absorbing cells of the unit.

As shown in Fig. 1, the device of the invention is intended for use for example in connection with a parachute supply drop arrangement such as may employ a parachute as indicated at 10 coupled to a load frame designated 12 which in turn supports a platform 14 upon which is mounted the supply load as indicated at 15. A series of ground impact cushioning cells or bags are mounted under the platform 14 in any suitably grouped arrangement, such as indicated at 16 in Fig. 1. As shown in more detail in Fig. 2, for example, the cells 16 may be aflixed to the bottom of the platform 14 by any suitable means such as retaining rings indicated at 18; and a base or bufler plate as indicated at 20 may be similarly atfixed to the bottom ends of the cells 16 to receive ground contact abrasion forces and to relatively position the lower ends of the cells as in the manner shown in Fig. 1.

The bottom plate 20 is apertured as indicated at 22 in communication with the interior of each cell, and a flapper valve device such as a flexible pad 24 is fixed to the base plate 20 over each aperture arrangement as by means of a fastener 26, whereby the members 24 are adapted to function as check valves to permit movement of ambient air through the apertures 22 into the interior of the cells 16 while restraining reverse movement thereof. Thus, it will be appreciated that whenever an aerial drop device as shown is launched from a flying airplane with the bottom plate 20 initially retracted aganst the platform 14, as the load falls toward the ground the bottom plate 20 will fall away from the platform 14 as to the position thereof as shown in Figs. 1 and 2. Thus, the cells 16 expand and ambient air flows through the apertures 22 to fill the interiors of the cells.

When the load reaches the ground the base plate 20 first contacts the ground and is thereby pressed upwardly to compress the air trapped within the cells 16 by the check valves 24; whereby the cells function to cushion the landing shock. However, in a system as so far described the landing energy-absorption capacity is strictly limited by the compressibility factor of the relatively small volumes of air entrapped in the cells; and the present invention contemplates an improvement in this respect through use of suitable means for momentarily supercharging the air cells at the time of ground contact, thus momentarily increasing the pressurization or supercharging the cells.

Although the invention contemplates any suitable means for supercharging the shock absorbing cells just prior to ground contact, such as may be energized by gas or liquid or powder or solid fuels, or the like; the drawing herein illustrates one practicable arrangement for that purpose. Thus, as shown in Fig. 2, a cartridge as indicated at 30 containing a pyrotechnic charge and arranged to be fired as by means of an igniter cap 32 for example may be mounted interiorly of each of the cells 16; conductors 34-36 being coupled to the igniters 32 as shown for firing the latter.

The invention contemplates generally a control system for ignition of the cell pressurizing charges such as includes a bob-weight cord or string releasable from the unit as it is jettisoned from the airplane, to train below the load as it approaches the ground and so arranged that as the bob-weight contacts the ground it initiates ignition of the cell pressurizing charges in anticipation of ground contact by the load unit. Furthermore, the invention contemplates that the bob-weight string arrangement shall include means whereby when the bob-weight first falls to the end of the string its momentum actuates (through the string) a switch or switches which presets the igniter control apparatus of the system so that upon subsequent slackening of the string (upon contact of the bob-weight with the ground) the switch mechanism is reversed to cause the igniters to be energized. Still further, the invention contemplates that the bob-string and switch mechanism shall include time-delay means accommodating initial bouncing of the bob-weight at the end of the bob-string prior to setting of the switch mechanism which subsequently responds to any slackening of the pull of the bob-weight to cause ignition of the pressurizing charges.

Thus, mechanism for controlling firing of the igniters may be arranged for example as shown in Figs. 2, 4, 5, 6; energization of the igniters being controlled by a switch mechanism such as it designated generally for example at 38 in Figs. 2, 4, 5. The device 38 comprises essentially a housing 40 carrying upon a pin 41 a spool 42 upon which is wound a cord 44 carrying at its lower end a weight 45 (Fig. l). The spool 42 is normally maintained on the pin 41 by means of a cotter pin 46 or the like, which is arranged to be withdrawn from holding position by pulling upon a cord 47 incidental to jettisoning of the device from the airplane. Thus, when the cord 47 is pulled to withdraw the cotter pin the spool falls free of the device and rolls down the string 44, as to the position shown in Fig. l; the cord 44 being of suitable length so that as the load carrying platform approaches the ground the weight 45 first contacts the ground so that the pull thereof is released from the cord 44 to initiate firing of the cartridges 30 in a predetermined distance-time relation to impact of the load with the ground, as will be explained more fully hereinafter.

As shown in Fig. 4, while the body of the cord 44 is wound upon the spool 42 the inner end of the cord slipfits through an aperture 48 of the housing 40 and is tied at its inner end to the actuating lever 59 of a pair of snap switches designated 52-54- respectively (Fig. 6). Whereas, the switches 52-54 are normally in the solid line positions shown in Fig. 6, while the unit is descending from an airplane with the weight of the bob-weight 45 pulling upon the cord, the cord operates to bias the switch actuator St) in such direction as to lift the switch arms 5254 to temporarily close the circuit through the heating coil 56 of a thermal type time delay relay device designated generally at 53 (Fig. 6). The circuit may be energized by any suitable source such as a battery as indicated at 6t), and constant energization of the heater coil 56 will thereupon cause the thermostat arm 62 of the relay 53 to close with contact 63 thereby energizing conductor 64. Then, when the bob-weight 4S strikes the ground the pull on the cord 44 is relaxed whereby the spring devices of the switch mechanism cause the actuator 50 to move the switches 52-54 to their broken line positions as shown in Fig. 6, thereby closing the circuit including the battery 60, relay switch arm 62, conductor 64, and the conductor 36; whereby an energy transmitting circuit through the igniter 32 is completed by means of the conductors 34, 36. This fires the igniter which in turn fires the cartridge 30 whereupon the gas products of combustion of the charge mingles with the entrapped air and the heeat generated upon combustion of the cartridge charge flash-heats the air and gases within the cell 16. This tends to expand and pressurize or supercharge the air and gases compressed within the cell due to the automatic closing of the check valve device 24. This action takes place rapidly and just prior t to the time of ground contact by the load carrying equipment. Although the drawing illustrates the firing circuit as being connected to only one igniter, it will of course be appreciated that the same circuit may be connected simultaneously to any number of igniters, as may be required depending upon the number of cells employed.

As explained hereinabove, the function of the timedelay device in the switch control circuit is to prevent preliminary setting of the mechanism so that relaxation of the bob-weight pull upon the string might cause ignition of the pyrotechnic charges during the period that the bob-weight tends to bounce at the end of the string 44 when first dropped. This bouncing action prevents adequate heating of the coil 56 for closing of the circuit through conductors 62, 64 until such time as the bobweight settles into a steady pull upon the string 44. Then, the relay closes and the device is set so that subsequent relaxation of the string pull will cause the cell charges to be fired.

Thus, in the case of the present invention supercharging of the cells is attained by means of a very inexpensive and light weight apparatus which functions independently of temperature changes and other operational variables. Another advantage of the system is that the cell devices do not need to be strictly air-tight because the supercharging pressure generation cycle is of relatively short duration, and the high temperature flashes from the pyrotechnic charges are adequately diluted by the relatively large volumes of air within the cells, so that thermal damage to the cells does not occur. Thus, it will be appreciated that the mechanism illustrated and described herein possesses many important features and advantages compared to conventional type bottled gas or motor driven compressor arrangements or the like. As shown at 70, frangible or other safety valve devices may be arranged in conjunction with the cells 16 if desired, to prevent rupturing thereof.

Therefore, it will be understood that although only one form of the invention has been shown and described in detail it will be apparent to those skilled in the art that the invention is not so limited but that various changes may be made therein without departing from the spirit of the invention or the scope of the appended claims.

What is claimed is:

l. A landing shock-absorbing load carrying device adapted to be dropped from a height, comprising a rigid load support member having a flexible normally collapsed cell mounted thereunder and a weight mass connected to the. bottom of said cell, said cell including check valve means permitting flow of ambient air thereinto under approximately atmospheric pressure conditions but resisting escape of air therefrom, a pyrotechnic charge device disposed Within said cell for heating of the air therein upon firing of said charge device, and a firing control device including a ground contact member operable upon ground contact to initiate firing of said charge for augmenting the gas pressure therein and heating of the air within said cell to develop a supercharged pressure condition therein for increasing the landing shock absorbing capacity thereof.

2. A load carrying device adapted to be dropped from a height, comprising a load support and a plurality of flexible cells mounted thereunder, said cells each including check valve means permitting flow of ambient air thereinto under approximately atmospheric pressure conditions but resisting escape of air therefrom, a pyrotechnic charge device disposed within each said cell for heating of the air therein upon firing of said charge devices, and a firing control device including a ground contact member operable upon ground contact to initiate firing or" said charges for augmenting the pneumatic pressures therein and heating of the air within said cells to develop supercharged pressure conditions therein for increasing the landing shock absorbing capacities thereof.

3. A load carrying device adapted to be dropped from a height, comprising a load support pallet and a flexible pneumatic cell mounted thereunder, said cell having a supply of air therein under approximately atmospheric pressure conditions, a pyrotechnic charge device disposed within said cell for heating of the air therein upon firing of said charge device, and a firing control device including a ground contact member suspended below said load support pallet and operable upon ground contact to initiate firing of said charge prior to ground contact by said load support pallet for augmenting the pneumatic pressure therein and heating of the air within said cell to develop a supercharged pressure condition therein for increasing the landing shock absorbing capacity thereof.

4. A load carrying device adapted to be dropped from a flying airplane, comprising, a load container and a flexible cell mounted thereunder, said cell including means permitting flow of ambient air thereinto under approximatcly atmospheric pressure conditions but resisting outflow thereof, a heater device disposed within said cell for heating of the air therein upon actuation of said heater. and a control device for said heater including a ground contact member suspended below said load container and operable upon ground contact to initiate operation of said heater for heating of the air Within said cell to develop a supercharged pressure condition therein for increasing the landing shock absorbing capacity of said cell.

5. A load drop device adapted to be dropped from a flying airplane or the like, comprising a load container and a flexible gas containing cell mounted thereunder, a heater device disposed Within said cell for heating of the gas therein upon actuation of said heater, and a control device for said heater including a ground contact member suspended below said load container and operable upon ground contact to initiate operation of said heater for heating of the gas Within said cell to develop a supercharged pressure condition therein for increasing the landing shock absorbing capacity of said cell.

6. A load drop device adapted to be dropped from a flying airplane or the like, comprising a load container and a flexible pneumatic cell mounted thereunder, a heater device disposed Within said cell for heating of the air therein upon actuation of said heater, and a control device for said heater including a suspension cord carrying a ground contact member suspended below said load container and switch means connected to said cord and operable in response to variations of the pull of said cord for control of an electric circuit controlling said heater, said circuit including time delay relay means operable to cause said circuit to be preset subsequent to a predetermined time lapse in response to pull upon said cord whereby upon subsequent ground contact of said contact member the relaxation of said cord will initiate operation of said heater for heating of the air Within said cell to develop a supercharged pressure condition therein for increasing the landing shock absorbing capacity of said cell.

References Cited in the file of this patent UNITED STATES PATENTS 557,396 Kindt 1 Mar. 31, 1896 1,882,416 Gastwirth Oct. 11, 1932 2,486,403 Hattan Nov. 1, 1949 FOREIGN PATENTS 499,409 Great Britain Jan. 24, 1939 604,938 Great Britain July 13, 1948 

